Today, netflow data collection is on a per node, per interface basis and is configured and managed for individual switches. The current approach has the following limitations. First, it is very difficult to correlate common (such as Tenant, Context (virtual routing and forwarding or VRF), Bridge Domains (BD)) and granular statistics (Application stats) across a network of switches, unless all the flow statistics go to the same collector. In a typical Application Centric Infrastructure (ACI) deployment, collecting fabric-level netflow statistics on virtual constructs such as the Tenant, VRF or BD is difficult, as the flows for these higher-level constructs will be spread across multiple switches in the fabric and these switches may be using different collectors for bandwidth scaling. Also, in a controller managed datacenter fabric, it is desired to collect finer statistics at various scopes than a traditional network. For instance, an administrator might want to collect statistics of a particular application for a tenant and multiple instances of this application can be running attached to different switches in the fabric. In general, fabric-wide granular netflow support will help provide meaningful information of application flows in the world of ACI.
Another limitation is the scalability and the management of the netflow collectors which cater to these set of the switches. In the current method, a flow collector is statically mapped to a netflow monitoring entity such as an interface on a switch. This method cannot scale when the bandwidth needs are different across different interfaces or switches. Also, when there are more collectors/switches, it becomes too difficult to manage the collector configuration. In a Dynamic Virtual Machine (VM) management environment, a collector should be able to cater to the VM moves. The same collector has to be provisioned across the entire domain where the VM could move.
As ACI ventures into cloud deployments, the requirement for an efficient netflow solution is even more compelling, as the fabric will be extended to support higher scale of virtual leaf switches and virtual PODs in the cloud. In this environment, managing netflow collectors per virtual leaf and maintaining a large number of collectors will be difficult.